Evaluation of the operating temperature and dynamic characteristics of a SOFC single cell

In this study, we experimentally studied our newly designed and built single cell and multi-cell high temperature (140°C∼180°C) polymer electrolyte membrane (HTPEM) fuel cell stack prototype at different operating conditions to investigate the effects of operating temperature, pressure and CO concentration on the cell performance. In particular, the effects of these parameters on the current-voltage characteristics of the fuel cell stack are investigated extensively. Experimental results obtained from both the single cell and multi-cell stack with high temperature PBI-based membrane show that the high CO tolerance at high operating temperature of HTPEM fuel cell stack makes it possible to feed the reformate gas directly from the reformer without further CO removal. In order to develop design parameters for fuel reformer, experimental data of this type would be very useful. The experimental results revealed the fact that a fuel reformer is a consumer of heat and water, and the HTPEM fuel cell stacks are a producer of heat and water. Therefore, the integration of the fuel cell stack and the reformer is expected to improve the entire system’s performance and efficiency. The results obtained from this study showed significant variations in current-voltage characteristics of HTPEM fuel cell stack at different temperatures with different CO poisoning rates. The results are promising to understand the overall system performance development strategy of HTPEM fuel cell in terms of current-voltage characteristics while fed with on-site reformate with different CO ratios in the anode fuel stream.

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Electron microscopy of keratinocytes cultured on a collagen substrate used as an allograft for the treatment of chronic wounds

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100130158 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1104-1105

Author(s):

Debby A. Jennings ◽

Michael J. Morykwas ◽

Louis C. Argenta

Keyword(s):

Electron Microscopy ◽

Cell Suspension ◽

Single Cell ◽

Chronic Wounds ◽

Mechanical Stability ◽

Uv Light ◽

Type I ◽

Single Cell Suspension ◽

Collagen Substrate ◽

Dermal Collagen

Grafts of cultured allogenic or autogenic keratlnocytes have proven to be an effective treatment of chronic wounds and burns. This study utilized a collagen substrate for keratinocyte and fibroblast attachment. The substrate provided mechanical stability and augmented graft manipulation onto the wound bed. Graft integrity was confirmed by light and transmission electron microscopy.Bovine Type I dermal collagen sheets (100 μm thick) were crosslinked with 254 nm UV light (13.5 Joules/cm2) to improve mechanical properties and reduce degradation. A single cell suspension of third passage neonatal foreskin fibroblasts were plated onto the collagen. Five days later, a single cell suspension of first passage neonatal foreskin keratinocytes were plated on the opposite side of the collagen. The grafts were cultured for one month.The grafts were fixed in phosphate buffered 4% formaldehyde/1% glutaraldehyde for 24 hours. Graft pieces were then washed in 0.13 M phosphate buffer, post-fixed in 1% osmium tetroxide, dehydrated, and embedded in Polybed 812.

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